A variety of reactions related to chemical and/or petroleum processing can be beneficially performed by exposing a feedstock to one or more fixed beds of catalyst within a reactor. Hydroprocessing is an example of such a process. Depending on the nature of the feed and the desired product, hydroprocessing can be used to remove contaminants such as sulfur and/or nitrogen; modify the boiling range of a feed to form higher value products; modify the properties of a feed, such as cold flow properties or viscosity properties; and/or saturate olefins and aromatics in the feed. Other examples of chemical and/or petroleum processing processes can include, but are not limited to, alkylation processes and oligomerization processes.
One potential difficulty with exposing a feedstock to one or more beds of catalyst in a reactor is that many types of reactions are exothermic. If a problem develops with flow within a catalyst bed, localized heating can occur that can allow a portion of a catalyst bed to reach an undesirable temperature, even though the overall reaction temperature may be within a tolerance limit. This type of temperature excursion can cause a variety of difficulties, such as deactivation of catalyst and production of undesired side products. Additionally, if sufficient excessive heating occurs, the excessive heating can potentially damage the internal structure of the reactor, or even lead to vessel failure.
German patent publication no. DE 19818693 describes a method for detecting temperature changes in a reactor. Long tubes containing a substance under pressure are located on the interior of the reactor. As the temperature increases, the pressure changes in the tubes can be detected. In some aspects, if a sufficient pressure is built up within a tube, the substance within a tube can cause the tube to rupture, leading to release of the pressure within the tube. Nitrogen is provided as an example of a substance to use within the tubes in the aspect where a tube may break open due to increased pressure.